HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION AND TANDEM MASS-SPECTROMETRIC IDENTIFICATION OF BREAKDOWN PRODUCTS ASSOCIATED WITH THE BIOLOGICAL HYDROLYSIS OF A BIOMEDICAL POLYURETHANE

As part of ongoing investigations into the biological degradation of b iomaterials, methods have been developed to isolate and chemically ana lyze polymer biodegradation products. The use of these methods can pro vide information on the biodegradation product profiles and yield conc entration levels for the isolated products. The latter information is required to assess the toxicological nature of biomaterials and their related degradation products. In this study a model biomedical polyure thane was synthesized with toluene diisocyanate, polyester diol and et hylene diamine, and then incubated at 37 degrees C in a biological sol ution containing enzyme. The biodegradation products were isolated fro m the in vitro system and prepared for HPLC analysis, by using a combi nation of ultrafiltration, freeze drying and liquid-solid extraction. The ultrafiltration and the liquid-solid extraction effectively remove d protein contamination. The separation of more than 20 degradation pr oducts, with gradient HPLC, was optimized using a photodiode array det ector. The separated degradation products were identified using a tand em mass spectrometer. The model polyurethane was labeled with C-14 in different segments, in order to assist in confirming the efficiency of the sample preparation and isolation methods. A detection limit of 2 ng was found. No toluene diamine - a suspected human carcinogen associ ated with some medical implants - could be found in the test samples. This represents a significant finding since the amount of this injecte d sample actually contained a total of 28 mu g of degradation products isolated from the incubation medium. (C) 1997 Elsevier Science B.V.